code: def wrap_dataloader(dl, dtype=np.float32):
      dl = OneHot(dl, index=1, nclasses=1000)
      dl = TypeCast(dl, index=0, dtype=dtype)
      dl = BGRMeanSubtract(dl, index=0)
      return dl
  
file_path: neon/examples/imagenet/data.py
imports: import numpy
  from neon.util.persist import get_data_cache_or_nothing
  from neon.data.dataloader_transformers import OneHot, TypeCast, BGRMeanSubtract
  from neon.data.aeon_shim import AeonDataLoader
label_desc: Use image node_id 2 for calling a global function with example usage: wrap_dataloader(dl, dtype) and returns: dl